Variable-speed gear for bicycles, tandems, and the like



Aug. 14, 1951 L. c. H. JUY 2,564,576

VARIABLESPEED GEAR FOR BICYCLES,

TANDEMs AND THE LIKE Filed March 11, 1947 Patented Aug. 14, 1951' UNITED OFFICE v VARIABLE-SPEED GEAR FOR BICYCLES, TANDEMS, AND THE LIKE Lucien Charles Hippolyte Juy, Dijon, France Application March 11, 1947, Serial No. 733,967 In France September 28, 1945 Section 1, Public Law 690, August 8, 1946 'Patent expires September 28, 1965 In the existing derailleur-type variable-speed gears for fbicycles, tandems and the like, one kind known as the double-turn kind, comprises a fixed point I supporting a selector pin on which is mounted a rocking lever 2 having at each extremity a tensioning pinion or roller 3 (Figure 1).

It is an object of the present invention to provide an improved gear of this kind in which removal of the rear wheel carrying the stepped pinions is considerably facilitated and in which the tension of the chain does not vary'with the diameter of the engaged pinion, an effect which is common to existing gears of this kind and which produces a difference in the output of the gear according to the speed selected.

In accordance with the present invention, a derailleur-type variable speed gear comprises an automatic tension-compensating device for providing a maximum arc of contact of the chain with the engaged pinion by a combined automatic action provided by an arm rockablymounted on a'iixed pivot on the frame and carrying at its free end a rockable lever having rollersor pinions for guiding and supporting the chain, the said arm and the lever being each independently urged in the required direction by a spring.

In order that the invention may be clearly understood and readily carried into effect, the same will hereinafter be more fully described with reference to the accompanying drawings, inwhich:

Figure 1 shows diagrammatically the known double-turn derailleur-type gear, in which the rocking lever and associated pinions or rollers rock about a fixed point in order to ensure the tension of the chain;

Figure 2 is a diagrammatic external view of an embodiment of the present invention, the parts being in the position in which the chain is in engagement with the small pinion, that is to say, in top gear;

Figure 3 is a View similar to Figure 2 with the parts in the position in which the chain is in engagement with the large pinion, that is to say, in bottom gear;

Figure 4 is a diagrammatic end view oi Figure 2;

Figure 5 shows diagrammatically a modified embodiment of the invention; and

Figure 6 is a detail sectional view yshowing the attachment of the tension spring of the moving arm.

Referring now to the drawings, which show only those parts of the gear whichare essential to a'clear understanding of the invention, the variable-speed gear embodying the present invention comprises essentially a rocking lever 4 which receives its transverse movement from a reciprocating device of known kind, and which is pvoted at 6 in order to ensure firstly that 6 Claims. (Cl. 74-Z17) 2 the roller 5 provides a suiiicient arc of contact of the chain B with the pinion 1, and secondly that the roller 51 produces the desired tensioning of the slack side of thechain 8.

The pivot 6 is itself carried by an arm 9 rockfably mounted on a shouldered screw I0 xed b`y a nut II on a bracket I2 secured to or integral with the rear bracket I3 of the frame. The

shouldered screw I0 serves to support freely an axial screw i4 which is threaded into the end'of a drum I5 on which is supported and wound a coiled spring I6, the fixed end of the spring engaging the drum I5 as at I6 and the other end |62 engaging the arm 9.

From the foregoing it will readily be understood that by turning the axial screw III to produce the rotation of the drum I5 the tension of the spring I6 is adjusted, this operation being carried out without locking the arm 9, which remains free' on the shouldered screw I0. The spring I 6 therefore acts in the direction of the arrow F (Figure 2) and tensions the moving arm 9 in the rearward direction. l

In its turn, the lever l is urged in the direction of the arrow F1 by the action of a spiral spring I1, one end of which is hooked over saidlever 4 while the other is hooked to the moving arm 9. The lever 4 and spring I1 are supported by the hollow pivot 6, the lever being connected to a control chain I8 which passes through the pivot 6 and is attached to a Bowden cable the sheath of which is lanchored to a pin 9 on the arm 9, The pivot of the arm 9 therefore forms an axis which is parallel to the axis of the rear road wheel carrying the stepped pinions and may even be coincident therewith. If this should not be the case, as in Figures 2, 3 and 4, the pivot I Il is adjacent to the road Wheel axis and is secured to the rear bracket I3 of the frame by a fixed bracket I2 of known kind.

It will be evident that the individual adjustment of the springs I6, I1, which are freely mounted respectively on the pivots IIJ and 6, the spiral spring I1 ensuring rotation of the lever 4 about the pivot 6, permits the tension of.A the chain 8 to be increased if the tension .of the Ycoiled spring I6 is increased with respect to that Yof the spiral spring I1, andinversely the tension of the chain 8 to be reduced and the are of contact' of the chain 8 on the engaged pinion increased if the tension of thespring I1 is increased with respect to that of the spring I6. 'I'his regulation may be obtained by.; for example, selection of the length of the respective arms of the lever 4, the disposition of said arms with respect to one another, the length of the arm 9, the angles at which the springs. are secured, and the rdiameters and quality of the spring wire, so as to achieve the desired result to the fullest possible extent. The tension of the springs I6 and desired by adjusting the tension of the conical spring I1, while the arc of contact of the chain 8 with the engaged pinion maybe varied by ad-` justing the tension of the coiled spring I6. This regulation is very important when pinions of very small diameter are employed. :The combination 'sponding ends of the latter, a* spring connecting the arm near its pivot with said pivot for urging the outer end of the arm in a chain tensioning direction and a further spring connecting the lever with a vpoint on the arm for urging the lever in a chain releasing direction.

of the regulation in the tension `of these two chain 8 without any danger `of accidental jump- Y iner of the chain, while providing a suicient arc of contact vto prevent the chain -from running -over the teeth when thesmaller pinion-s are be- In the modication shown inFigure 5, a rockable lever I9 having unequal arms is employed, the ulcrum 22 of which is so located on the moving arm 91 that the tension in the direction of the arrow F3 itself determines the arc 0i contact O f the chain 81, the roller -20 Abeing placed under pressure by reaction of the roller 2 I, thereby enabling the spring II to be dispensed with or its tension to be reduced. y

With either of these arrangements, removal of the rear wheel is facilitated, since when it is pulled forwardthe arm 9 is inclined to the rear by its spring, whereby theniechanismis disengaged and the chain is heldin position ready for rie-assembly.

.I claim:

1. In a Variable speed gear vfor cycles and the likef vehicles includingchaindriven sprocket wheels on the rear wheel, the combination of a bracket rigid With the vehicle frame in the vicinity of the rear wheel axis, a pivot on said bracket,

4an armV pivotally secured to said pivot, a lever pivotally secured tothe free end of said yarm, 'chain rollers adapted to-engage the driving chain and pivotally carried by the lever at the corresponding ends of the latter, a spring connecting the arm near its pivot with said-pivot for urging -A the Outer end ofthe .arm ina chain tensioning direction and means for adjusting the tension of said spring. 1

2. In a variable speed gear for cycles and the iikevehicles including -chainV driven sprocket wheels on the rear Wheel, the combination of a bracket .rigid With the vehicle frame in the vicinity of the rear wheel axis, a pivot onfsaid bracket ata distance from the axis of the sprocket wheels smaller than the radius' of the larger sprocket'l wheel, an arm pivotallysecured to said pivot, a lever pivotally secured to the free end of said arm, chain rollers adapted to engage the driving chain and pivotally carried by the lever at the corresponding ends of the latter, a spring connecting the arm near its pivot with said pivot for urging the outer end of the arm in a chain tensioning Adirection and means for adjusting the tension of said spring.

3. In a variable speed gear for cycles and the like vehicles including chain driven sprocket wheels 'on the rear wheel, the combination of a bracket rigid with the vehicle frame in the vicinity of the rear Wheel axis, a pivot on said bracket, van arm pivotally secured to said pivot, a lever pivotally secured to the free end of said arm, chain rollers adapted to engage the driving chain and pivotally carried by the lever at the corre- 4. VIn a variable speed gear for cycles and the like vehicles including chain driven sprocket wheels on the rear wheel, the combination of a bracket rigid with the vehicle frame in the vicinity of the rear Wheel axis, a pivot on said bracket, an arm pivotally secured to said pivot, a lever pivotally secured to said pivot, a lever pivotally secured to the free end of said arm, chain rollers adapted to engage the driving chain and pivotally carried by the lever at the corresponding ends of the latter, a spring connecting the arm near its pivot with said pivot for urging the outer end of the arm in a chain operating direction, another spring connecting the lever with a point of the arm for urging the lever in a chain operating reaction opposed to the last mentioned direction and means for adjusting the tension of at least one spring.

5. In a variable speed gear for cycles and the like vehicles including chain driven sprocket Wheels on the rear Wheel, the combination of a bracket rigid with the vehicle frame in the vicin- -ity of the rear wheel axis in a direction substantially radial with reference to said Wheel axis, .a pivot on said bracket, an arm pivotally secured to said pivot, a lever pivotally secured to the free end of said arm, chain rollers adapted to engage the Vdriving chain and pivotally carried by the -lever at the corresponding ends of the latter, a

spring connecting the arm near its pivot with rsaid-pivot for urging the outer end of the arm in a chain tensioning direction and aiurther `spring connecting the lever with a point on the larm for urging the lever in a chain releasing directionl and means for adjusting separately said two springs.

6.Y In a variable speed gear for cycles and the like vehicles including chain driven sprocket Wheels onthe rear wheel, the combination of a bracket rigid with the vehicle frame in the vicinity of the rear wheel axis, a pivot on said bracket, an arm pivotally secured to said pivot, a lever pivotally secured to the liree end of said arm, chain rollers adapted to engage the driving chain and pivotally carried by the lever at the corresponding ends of the latter, a spring connecting the arm near its pivot with said pivot for urging the outer end of the arm in a chain tensioning direction and a further spring connecting the lever With a point of the arm for urging the lever in a chain releasing direction, and means for adjusting vseparately said two springs.

VLUCIEN CHARLES HIPPOLYTE JUY.

REFERENCES CET-ED The following references are of record in the file of this patent:

UNITED STATES yPATENTS 

